And when you close them you are probably asked if you want to save them. Do you answer 'yes'? Then it should take some time to save 20 products. What's not good is that everything is frozen. By everything, do you mean everything in SNAP or everything of the OS. It is normal that you can't work with SNAP while writing one or more products. You should see a progress dialog, but it should not be frozen. Are you already working with SNAP 5.0?